Historically, black body radiation in the tungsten filament lamp was our primary industrial means for producing 'artificial' light, as it replaced gas lamps. Solid state luminescent devices for applications ranging from lamps to displays have proliferated since then, particularly owing to the develop ment of semiconductors and phosphors. Our lighting products are now mostly phosphor based and this 'cold light' is replacing an increasing fraction of tungsten filament lamps. Even light emitting diodes now chal lenge such lamps for automotive brake lights. In the area of information displays,...

Historically, black body radiation in the tungsten filament lamp was our primary industrial means for producing 'artificial' light, as it replaced gas lamps. Solid state luminescent devices for applications ranging from lamps to displays have proliferated since then, particularly owing to the develop- ment of semiconductors and phosphors. Our lighting products are now mostly phosphor based and this 'cold light' is replacing an increasing fraction of tungsten filament lamps. Even light emitting diodes now chal- lenge such lamps for automotive brake lights. In the area of information displays,...